The traditional syringe comprises an injecting needle but without any safety device. It is able to reuse and easily result in drug and blood contamination. In addition, the exposed needle is further easily stabbing medical personnel and cleanup personnel to make the infectious disease be infected much more. In accordance with the problems of the traditional syringe, how to develop a syringe to prevent from reusing and making secondary contamination is expected.
The recently retractile safety syringe is fastened at the open end of the barrel tightly. It is easily resulting from outside temperature, such as deteriorating the suitability between the needle set and the barrel to result the needle set indentation and leakage when injecting from a sharp raise in temperatures, or overtightening the needle set and the barrel to result the needle and the needle set incapable of retracting in the barrel from the sharp fall of temperature. Therefore, the quality control of the syringe is failed and further the yield rate is decreased.